One popular method of fishing, which is the only practical method for certain species of fish, is trolling. When trolling, one pulls a lure, attached to the rod line, behind a moving boat. One problem with trolling is how to keep the lure at a desired depth. The depth is determined by a number of factors, including the length of line, the trolling speed, the diameter of the line, the weight of the line and the weight, configuration and buoyancy of the lure. Although one could merely use a very heavy lure or heavy weight attached to the line to achieve the proper trolling depth, this would severely hinder playing any fish caught. Thus there have been many different schemes and equipment developed to keep the lure at the required depth and yet retain relatively unrestricted action when playing a fish.
One method of doing so is through the use of a downrigger. Downriggers include a short pole and reel by which a heavy weight is suspended over the side of a boat at the end of the downrigger's line. The rod line is secured to the downrigger line near the weight by a tension release clip. When a fish strikes the lure at the end of the rod line, the increased tension on the rod line causes the tension release clip to open. This releases the fishing line so the fish can be played freely.
Although downriggers can work well, missed strikes or temporary snags require the lure and downrigger weight to be retrieved to reconnect the rod line to the downrigger line. Also, downriggers are somewhat expensive and add an extra level of complexity to fishing. In lieu of downriggers, a heavy weight can be attached between the rod line and the leader connecting the lure by a special clip. When a fish strikes the lure, the leader makes a sudden pull on the clip which releases the weight. The weight drops to the bottom. This, although simple, can be quite expensive.
Instead of downriggers and disposable weights, trolling divers can be used. Divers are placed between the end of the rod line and the leader attached to the lure. Divers all include a planing surface normally disposed at an angle to the horizontal so when they are pulled through the water they drag down or depress the lure. Since doing so creates a large drag on the rod line, they are designed to change from their set or diving attitude to an unset or climbing attitude when a fish strikes the lure. When unset the planing surface becomes aligned with the rod line to substantially reduce the drag and allow the fish to be played freely.
Some divers, once unset, must be retrieved, removed from the water and manually reset by the user. See, for example, U.S. Pat. No. 3,643,370 to Cook and Davis. Other divers, such as shown in U.S. Pat. Nos. 3,808,727 to Flanders, 3,447,255 to Walden and 3,813,809 to Frotiee can be reset by the user while in the water. However, the diver shown in Flanders, Walden and Frotiee patents cannot be unset at will by the user. That is, if it is desired to retrieve the lure rapidly, such as can occur when a fishing partner is playing a fish or when coming near underwater obstructions, the divers remain in their diving attitude thus keeping the lure deeply submerged and making retrieval tedious and tiring.
U.S. Pat. No. 3,898,759 to Jensen discloses a diver which, in theory, can be unset by a fisherman sharply tugging on the rod line. An embodiment similar to the embodiment disclosed in the patent, including the auxiliary fin shown in FIGS. 6 and 7, was marketed for a time as the DOLPHIN. Applicant has found that once unset, the DOLPHIN trolling diver is difficult to keep unset. Only by reeling in the rod line very rapidly, which can be difficult to do for many, will the DOLPHIN remain unset.
The trolling diver sold by BIG JON of Travers City, Mich., covered by U.S. Pat. No. 3,908,299 to Kalberer, provides for the automatic resetting of the diver after a missed strike and permits the user to unset the diver at will by increasing the pull on the rod line. However, in distinction to the DOLPHIN diver, the BIG JON diver remains unset at only moderate speeds of line retrieval. Although the BIG JON trolling diver does fulfill all the desirable objectives for a user controlled diver, it does have a minor shortcoming. Sometimes its lines get tangled, which usually requires the user to retrieve it and manually untangle the line.